1. Field of the Invention
This application relates to electrical connections and, more particularly, to a method for effecting electrical connections such that an improvement in the transmission properties of a connectorized flat cable interconnection assembly is achieved.
2. Description of the Prior Art
Oftentimes coaxial cables are used to effect the interconnection of many high-speed or broadband circuits. Such cables are expensive, bulky and difficult to terminate on multilayer backplanes comprised of a field of interconnection pins. Attempts to reduce the amount of space needed has led to the use of flat cable interconnection assemblies.
One illustration of the extent to which flat calbes have been employed for interconnection purposes is contained in an article entitled "Interconnection Systems--Mass Termination Schemes Make Flat Cable Economically Viable," appearing in EDN magazine, Sept. 20, 1975, at pages 22 through 29. While the use of flat cable results in certain economies of space, oftentimes the transmission characteristics are less than optimal.
In an attempt to improve the transmission characteristics, various signal patterns have been proposed for application to flat cable. For example, in J. T. Kolias, U.S. Pat. No. 3,591,834, issued July 6, 1971, a signal arrangement comprised of alternating signal leads and ground leads is disclosed. While this signal distribution results in some improvement, many of the transmission characteristics, such as bandwidth, cross-talk, impedance match, and the like, are not so significantly improved as to make flat cable interconnection a viable alternative to coaxial cable.
Some improvement in the impedance matching characteristics of connectors was effected by I. L. Fergusson and is disclosed in his U.S. Pat. No. 3,634,806, issued Jan. 11, 1972. Fergusson relates to a match impedance connector which prevents an impedance interruption when multiconductor flat cable is connected to a printed circuit board. The connector block has two staggered rows of molded cavities into which are inserted a plurality of connector pins. The connector pins are electrically connected to alternate signal and ground conductors of a multiconductor flat cable. A metallic plate is disposed between the two rows of connector pins and is connected to the ground pins. While Fergusson's connector represents a step in the right direction, little attention is given to effecting improvements in the transmission characteristics of the media interconnecting such connectors.
Accordingly, it is one object of the present invention to improve the transmission properties of a connectorized flat cable interconnection assembly.
It is another object to decrease the amount of crosstalk between adjacent assemblies.
A further object of the present invention is to control the impedance matching characteristics throughout the length of the interconnection assembly.
Still another object is to improve the usable transmission bandwidth of a flat cable interconnection assembly.
Yet a further object of the present invention is to reduce the cost of a flat cable interconnection assembly.
An even further object is to increase the packaging density achievable through the use of flat cable interconnection assemblies.